Known in the art are various techniques and devices for collecting sap from a tree, for example from a maple tree. Over the years, the practice of collecting sap from trees has been refined and improved through the use of new devices and fixtures, and at least since the 1960s, by using vacuum recovery systems.
Canadian patent No. 2,233,739 discloses a vacuum recovery system including a tubular network connected to the sap-collecting devices affixed to the various trees so as to direct the sap that is collected towards reservoirs. The tubular network is connected to a pump creating vacuum conditions so as to provide a quick flow of sap from the tree to the reservoirs.
Sap collection devices, an example of which is schematically shown in FIG. 1, have changed relatively little over the years, and still present some disadvantages.
Conventional devices are hard and are inserted into the tree by a hammer pounding on one end, which is similar to a tapered punch. This can cause damage to the tree.
Furthermore, conventional devices often create small vertical cracks on either side of the tapped holes when they are inserted into the tree. These cracks accumulate water, and after various freeze/thaw cycles, especially during sustained cold weather conditions, the cracks tend to become larger, which results in the device becoming loose in the tapped hole and falling out. The cracks can also cause water to accumulate between the bark of the tree and the cambium so that when water freezes, the bark of the tree tend to lift, thereby causing further damage to the tree. After becoming loose, the device must be reinserted into the tapped hole by a hammer, which can cause further cracking, thereby perpetuating the cycle of cracking/reinsertion. After a certain number of these cycles, the tree is exposed to the elements and the liquid contained therein “dries up” or freezes. Furthermore, air is introduced between the collecting device and the tapped hole, which reduces the effectiveness of the closed vacuum system and thus the amount of sap that can be collected.
Cracks are known to reach a size of up to 10 square inches on both sides of a tapped hole, as shown schematically in FIG. 2. These cracks and the areas over which they propagate can cause significant damage to the tree being tapped, especially when multiple holes are made in the same tree. A further disadvantage caused by the cracking/reinsertion cycle is the need of additional labour to reinsert the sap-collecting devices repeatedly, often during cold weather conditions. Over time, there is a decrease in the tree's productivity (i.e. less sap collected for a given number of tapped holes).
Hence, there was clearly a need for an improved device to overcome or at least minimize some of the aforementioned problems.